SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '305f759ec0960035523bbde0b921f6767f836ade8a92f06df00984ad034fd76d' 
  AND token = 'CWjnPJJuI4d2PZHssvUpdYAfnyLw1yjs6YWxJ/Rck8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}